Most modern vehicles include some sort of driveline differential to compensate for travel differences between wheels on common axles during turns. The differential usually includes a pinion bearing assembly with one or two bearings journaled onto a pinion shaft. Driveline bearings are lubricated with high-viscosity oil to cool the bearing assembly during operation. This oil can cause parasitic losses. This is especially true during a vehicle cold-start or when the bearings are at a relatively low temperature. For example, in some instances it can take 20 minutes for an entire driveline differential to reach a relatively warmed temperature. During that time, the losses in the bearings can be two to three times greater than the losses when the bearings are warmed. Accordingly, there is a need to reserve heat in the bearing assembly so that the time required to warm-up the entire bearing assembly after cold starts is significantly reduced.
Thermal insulation for bearings has been used before to isolate the bearing from heat exhausted from neighboring components. For example, U.S. Pat. No. 5,687,618 titled “Flywheel Assembly” teaches the use of an insulation member on a ball bearing for a flywheel torsional damper. This, however, does not pertain to vehicle driveline differentials.
It is therefore desirable to have a vehicle driveline differential with improved efficiency during cold starts.